The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In the recovery of hydrocarbons from subterranean formations, it is often necessary to apply various treatment procedures to the well to improve the life and/or the productivity of the well. Examples of the treatment procedures include, but are not limited to, cementing, gravel packing, hydraulic fracturing, and acidizing. Particularly, in formations with low permeability, it is common to fracture the hydrocarbon-bearing formation to provide flow channels. These flow channels facilitate movement of the hydrocarbons to the wellbore so that the hydrocarbons may be recovered from the well.
Fracturing has historically been an operation where the materials that were going to be pumped were prepared on location. Deliveries of liquids, proppant, and chemicals were all accomplished before the job began. Specialized storage equipment was normally used for handling the large quantities of materials, such as sand chiefs made by Besser. Similarly, specialized tanks such as water tanks and frac tanks were used for liquids. These tanks are typically the largest possible volume that can be legally transported down the road without a permit. Once everything was ready, more specialized equipment was used to prepare gel, mix in proppant, dose with chemicals, and deliver the resulting fluid to the fracturing pumps under positive pressure. All of these specialized well site vehicles and units are expensive, and lead to a very large footprint on location.
FIG. 1A illustrates a wellsite configuration 9 that is typically used in current land-based fracturing operations. The proppant is contained in sand trailers 10 and 11. Water tanks 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 are arranged along one side of the operation site. Hopper 30 receives sand from the sand trailers 10,11 and distributes it into the mixers 26, 28. Blenders 33, 36 are provided to blend the carrier medium (such as brine, viscosified fluids, etc.) with the proppant and then transferred to manifolds 31, 32. The final mixed and blended slurry, or frac fluid, is then transferred to the pump trucks 27, 29, and routed at high pressure through treating lines 34 to rig 35, and then pumped downhole.
Referencing to FIG. 1B, a conventional fracturing operation 100 is illustrated schematically. The operation 100 includes a water tank 102 and a polymer supplier 104. The water tank is any base fluid including, for example, brine. The operation 100 may include a precision continuous mixer 106. In certain embodiments, the precision continuous mixer 106 is replaced by an operation 100 where the polymer is fully mixed and hydrated in the water tank 102. It can be seen that, where the polymer is pre-batched, very little flexibility to the size of the fracturing operation is available. For example, if an early screen-out occurs, a large amount of fracturing fluid is wasted and must be disposed. The operation 100 further includes an operation 108 to slowly agitate and hydrate the fracturing fluid, which may occur within a residence vessel or within a properly sized precision continuous mixer 106. The operation 100 further includes a proppant 110 mixed with the hydrated fluid, for example at a high-speed blender 112 that provides the proppant laden slurry to fracturing pumps. The operation 100 further includes an operation 114 to pump the slurry downhole.
It can be seen from the operation 100 that various equipment is required at the location, including the water tanks, a chemical truck or other vehicle carrying the polymer and/or other additives, a continuous mixer, a proppant vehicle (sand truck, sand chief, etc.), a blender (e.g. a POD blender), and various fracturing pumps. Alternatively, the continuous mixer may be replaced with equipment and time to batch mix the fracturing fluid into the water tanks in advance, increasing the operational cost, reducing the flexibility of the fracturing treatment, and increasing the physical footprint of the fracturing operation. Also, a large amount of water is needed for a fracturing operation, which leads to the generation of a large amount of flowback fluid. The storage, management, and disposal of the flowback fluid are expensive and environmentally challenging.
The current application addresses one or more of the problems associated with the conventional fracturing operation.